Silicon carbide is expected to be used as a material for next-generation semiconductor devices. Silicon carbide has better physical properties than does silicon in that the band gap is 3 times, breakdown electric field intensity is about 10 times, and thermal conductivity is about 3 times that of silicon. When these characteristics are utilized, metal oxide semiconductor field effect transistors (MOSFETs) or insulated gate bipolar transistors (IGBTs) capable of operating at high breakdown voltage, at low loss, and at high temperature can be realized.
For example, when the MOSFET is short-circuited across the silicon carbide region due to malfunction of a circuit, a large voltage is applied between a source and a drain, and thus a large current flows. Similarly, when the IGBT is short-circuited, a high voltage is applied between an emitter and a collector, and thus a large current flows. A time from the short-circuit state to a breakdown of the MOSFET or the IGBT is referred to as short-circuit tolerance. In order to prevent the breakdown of the MOSFET or the IGBT when the MOSFET or the IGBT is short-circuited, it is desirable to improve the short-circuit tolerance of the device.